Machine for cutting unbreakable watch crystals



May 13, 1930. M. c. CAMPBELL 1,757,952

MACHINE FOR CUTTIQNG UNBREAKABLE WATCH CRYSTALS FilzkDec. 5, 1927 2 Sheets-Sheet 1 IIIIII/l/I/I/l/If May 13, 1930. I M. c. CAMPBELL 1,757,952

MACHINE FOR CUTTING UNBREAKABLE WATCH CRYSTALS Filed Dec. 5, 1927 2 Sheets-Sheet 2 Z5 Z6 Z4 ill/822257 Patented May 13, 1930 oFFicE] MILTON C. CAMPBELL, OF CHICAGO, ILLINOIS MACHINE FOR CUTTING UNBREAKABLE WATCH CRYSTALS Q Application filed December 5, 1927. Serial No. 237,725.

This invention relates to the manufacture of unbreakable watch crystals for watches and it has for its object to provide a simple, compact and accurate machine which can be operated without especial skill to cut unbreakable crystals for watches of proper size and shape to fit the watch cases for which they are cut.

Another object is to insure accuracy of fit by providing means whereby the watch case for which the crystal is to be cut is used as a pattern to cause the cutting tool to follow a line of cut on the crystal blank corresponding exactly with the bezel of the watch case so that the cut crystal will fit accurately and snugly in the bezel frame without further work.

Anda further object is to provide for easily securing the blank and the watch case to be 2 fitted in the machine in proper position for cutting the crystal, and simple means for adjusting and operating the cutting tool so that a crystal can be accurately made and inserted in" the crystal frame of the watch case 2 withoutrequiring especial skill or experience and as a quick repair job.

In the accompanying drawings illustrating a selected embodiment of the invention, Fig. 1 is a top plan view of the machine.

Fig. 2 is an elevation of the chuckend of the machine. Fig. 3 is a detail view showing the cutting tool in operative engagement with the blank. Fig. 1 is an elevation of the cutting end of .35 the machine.

Fig. 5 is a sectional view on the line .5 of Fig.1.

Figs. 6, 7 and 8 are detail perspective views of parts of the chuck, and i Fig. 9- is a detail view showing how the cutting operation is guided and controlled by the bezel of the watch case to receive the crystal.

Referring to the drawings the machine comprises a main frame l0 having a drive shaft 11 mounted therein and provided with an operating handle 12. The drive shaft is provided with a worm 13 which drives the worm gear 14 secured on the main shaft 15 which is mounted in the frame.

A self centering chuck is mounted on one end of the main shaft and it comprises a body in the form of a circular disk 16, Fig. 7, having in one face a guide groove 17 to receive the guide blocks 18 rigid with the jaws 19. An adjusting plate 20 is located at the back of the disk 16 and it is provided with cam slots 21 to receive bolts 22 which pass through slots 23 in the disk and engage the jaws. Oppositely disposed handles 24; are provided at the periphery of the adjusting plate and springs 25are connected to pins 26 attached to the adjusting plate and to pins 27 attached to the disk 16. I prefer to provide two pairs of springs 25, two springs being connected at their ends to each pair of pins 26, 27 because I find this provides a more even and uniform tension than would be provided with single springs. 'It will readily be understood that by turning the adjusting plate 20, by grasping one of the handles 24, the bolts 22 will be caused to travel in the cam slots and move the jaws 19 away from each Ot-llSL and after pressure on the handle is released the springs will move the jaws toward each other and clamp them upon the article inserted therein. The jaws slide and are guided in the groove 17 in the disk body 16 and will always be maintained in proper relation to each other.

On the other end of the main shaft 15 a holder 28 is mounted to receive and hold a blank 29 from which the crystal is cut. This blank may be made of celluioid or other unbreakable material and it is provided with a centrally disposed dome and with openings to receive the securing and holding pins 30 as more fully described in my application. Serial No. 237,724, filed concurrently herewith. To accommodate the dome the holder is provided with a recess 31. The pins 30 are located diametrically of the holder to fit accurately the openings provided for them in the blank, and these parts are desirably made with a high. degree of accuracy to secure the best results. The dome is centrally disposed in the blank and the openings to receive the pins are located equi-distant from the center of the blank and the dome. The pins and the openings are made to register one with the other, and they are likewise made to fit snugly, so that when the blank is mounted on the holding pins it will be held rigidly by these pins in its proper position on the holder so that the cutting tool will cut on a true line according to the bezel in the watch case or crystal frame held in the chuck.

A shaft 32 mounted in the main frame and carrying rigid arms 33 and 3a constitutes a cutter frame which can be swung to and from operative position to bring a tracing tool 35 into operative relation with the watch case or crystal frame in the chuck and a cutting tool 36 in operative relation to the blank in the holder. The tracing tool is rigidly secured in the arm 3l by a screw 37. The arm 34 is provided with a diagonal slit 38 extending in the general direction of its length and through its outer free end. The tracing tool 35 is mounted in the larger end portion of the arm and a screw is threaded in the smaller end portion of the arm and engages the larger end portion of the arm to provide for a line adjustment of the tracing tool for correct alinement with the cutting tool. A collar 40 is arranged on the shaft 32 between two rigid parts 41 of the main frame and when the shaft is adjusted longitudinally a set screw 42 may be tightened to prevent longitudinal movement of the shaft during the cutting operation. An additional collar 43 may be provided on the shaft to be locked against a part of the frame for assisting in holding the shaft against longitudinal movement, if desired.

The cutting tool 36 is mounted on a spring pressed plunger l4: which operates in a bore in the end of the arm 33. A pin 46 on the plunger is arranged to engage the shoulder l? at the outer end of the bore to hold the cutting tool in retracted position, and to enter the slot 48 when the cutting tool is released for operation. A relatively long flat spring -19 is fastened by a screw 50 at its rear end to the arm 33 near its rear end and the front end of this spring is forked to engage the groove 51 in the plunger i l. The spring 49 may be tensioned by a screw 52 which operates through the arm 33 upon the spring adjacent its rear end. The spring holds the cutting tool to the work.

In practice, when it is desired to cut an unbreakable crystal from a blank for a particular watch, the watch case, or the crystal frame thereof, is clamped in the chuck as indicated generally at 53, Fig. 2. No particular care is required to arrange the watch case or the crystal frame in the chuck except to see that it is secured in rigid position by the jaws. After the tracing tool has been proper y set the collar 40 is secured to the shaft 32 by adjusting the screw l2, and if a collar 43 is provided it may also be secured in set position. A blank having a dome of a proper size and shape for making the crystal is secured on the holder pins 30 with the convex side of the dome located in the recess 31 of the holder. The tracing tool has been properly alined with the cutting tool for accurate work and it is now engaged with the bezel in the crystal frame so that it will ride free thereon and in contact therewith throughout the revolution of the chuck since the cutting operation should be performed in one complete cycle of operation of the main shaft 15. The plunger 14 is then released and the cutting tool 36 is carefully engaged with the blank 29. The spring 4E) holds the cutting tool under proper tension in engagement with the blank, and this tension is controlled by the set screw 52. Then the crank 12 is turned to revolve the main shaft 15 and the watch case or crystal frame is caused to make a complete revolution during which the tracing tool engages the bezel and the cutting tool scores or cuts the blank 29 in exact correspondence with the shape of the crystal opening in the frame of the watch case. In Fig. 4 l have indicated a line of cut in broken lines at 54 which corresponds with the shape of the crystal opening in the watch or crystal frame 53.

My machine can be used for making crystals in quantities but it is particularly adapted for use by jewelers, watch repairers and others for making crystals to repair watches quickly. No particular skill or experience is required in operating the machine except to set the tracing tool properly in the bezel and to turn the crank. The weight of the cutting frame is suiiicient to hold the tracing tool in engagement with the bezel on the angles and curves well as on the straight sides thereof, and is also sufiicient to hold the cutting tool to the work in position to cut out a crystal which will exactly lit in the bezel. It is not intended that the cutting tool should completely sever the blank but only to score it sufficiently deep to enable the crystal to be pushed out of the blank after the cutting operation is complete. I have found in the practical use of the machine that crystals of different shapes may be cut with desired precision and accuracy for fitting the bezels of crystal frames of all the known shapes, regardless of the number and kind of curves and angles and this makes it especially important and desirable for those called upon to replace crystals in watches because it enables the work to be done quickly and promptly regardless of the shape of the crystal required.

I have shown and described the machine in a form which has been found entirely satisfactory in practical use but I reserve the right to make such changes in the form, construction and arrangement of the parts within the scope of the following claims.

I claim:

1. A machine of the character described,

comprising a frame, a rotary shaft mounted horizontally in said frame, means for turning said shaft, a chuck on one end of said shaft adapted to hold a watch or watch bezel, a holder on the opposite end of said shaft for a blank from which to cut a crystal, a follower adapted to follow the edge of the crystalreceiving recess of the bezel, a tool arranged to act on a blank carried by said holder, and a mechanical connection between said follower and tool to cause the tool to cut a crystal for use in the bezel as said shaft is rotated to synchronously turn the chuck and holder.

2. A machine of the character described, comprising a frame, a rotary shaft mounted horizontally in said frame, means for turning said shaft, a chuck on one end of said shaft adapted to hold a watch or watch bezel, a holder on the opposite end of said shaft for a blank from which to cut a crystal, a rockshaft mounted on said frame parallel to the first-named shaft, two arms extending from said shaft to swing vertically adjacent said chuck and holder respectively, a follower carried by one arm to follow the edge of the crystal-receiving recess of the bezel, and a tool carried by the other of said arms to act on a blank carried by said holder, as the first shaft is rotated to synchronously turn the chuck and holder.

3. A machine of the character described, comprising a frame, a rotary shaft mounted horizontally in said frame, means for turning said shaft, a chuck on one end of said shaft adapted to hold a watch or watch bezel, a holder on theopposite end of said shaft for a blank from which to cut a crystal, a follower adapted to follow the edge of the crystal-receiving recess of the bezel, a tool arranged to act on a blank carried by said holder, a mechanical connection between said follower and tool to cause the two to move in harmony and thereby cause the tool to cut a crystal for use in the bezel as said shaft is rotated to synchronously turn the chuck and holder, means mounting said follower on said mechanical connection whereby the follower will be normally resiliently urged toward said bezel, and means for holding said follower away from said bezel against the action of its urging means.

4. A machine of the character described comprising a frame, a rotary shaft mounted horizontally in said frame, means for turning said shaft, a chuck on one end of said shaft,

adapted to hold a watch or watch bezel, a holder on the opposite end of said shaft for a blank from which to cut a crystal, a follower adapted to follow the edge of the crystal-receiving recess of the bezel, a tool arranged to act on a blank carried by said holder, a mechanical connection between said follower and tool to cause the two to move in harmony about a common axis and thereby cause the tool to cut a crystal for use in the bezel as said shaft is rotated to synchronously turn the chuck and holder, said connection including means whereby the tool and follower may be slightly relatively adjusted about their said common axis.

MILTON C. CAMPBELL. 

